I'm willing to accept that based on what other people have posted before me that my post was probably over the top. It was largely a reaction to seing a fair number of these kinds of threads where people declare an anime with even the slightest philosophical bent to be the immensely deep and meaningful. >>18, what you recommended did fit the bill in terms of being similar in style to the ones mentioned by the OP, so I wasn't really criticising recommending Gantz etc. It's just I was a bit taken aback by the whole notion anime being something you can be pretentious about from an intellectual standpoint.
Mild spoilers for Gantz and NHK follow
NHK is really well done and I really enjoyed it, however I would have reservations about claiming that it provided a sincere analysis of contemporary problems. It was a very light hearted satire that won most of it's praise simply for not being such a rose-tinted view of anime otakus as most of it's contemporaries (Geshiken etc.). When it raises serious issues (suicide clubs, pyramid schemes, etc) it rarely takes them seriously, you might get a minute of sad music as you find the class presidents lost all her money, but that's usually as far as it goes. NHK was nearly an unflinching look at social poblems but repeatedly bottled out at the last minute.
I think I wasn't really clear enough about NHK and NieA_7; what I was saying was that they are not childish, but they lack the depth that I feel is necessary to justify calling something highly intelligent.
Gantz was quite a nice idea but seemed far too busy with chopping people in half. It would have been great to really focus on the characters disbelief with their situation and how they were dealing with it, particularly how Kishimoto coped with being a copy of herself. Instead the show focused on the game or whatever it was they were doing and never really got round to answering any of the questions it (could have) proposed. While I'm all for mysterious enigmatic anime the complete absence of answers in Gantz meant it kind of dribbled out.
If I were pressed to make a recommendation I'd say Angel's Egg or Night on the Galactic Railroad, buts theres plenty of other things in this thread already which more than qualify (thanks for linking the jolly rodger torrent). All I'm really objecting to is the idea that or something to appeal to adults it has to be profound and meaningful, resulting in people who like something childish claiming it has hidden depths. The fact that Honey and Clover and Samurai Champloo have both been put forward in this thread as examples of intelligent anime clearly shows this stigma is alive and kicking.